The Messenger of Allah ﷺ said, "The Muslims will soon be besieged and driven back to Medina, until the farthest of their frontier outposts is Salah."
قال رسول الله ﷺ: يوشك المسلمون أن يحاصروا إلى المدينة حتى يكون أبعد مسالحهم سلاح.
Abu Dawud (4250) narrated it, and Ibn Hibban (6771) and Hakim (4/511) both graded it sahih, all of them through routes from Ibn Wahb, who said, Jareer bin Hazim narrated to us, from Ubaydullah bin Umar, from Nafi, from Ibn Umar, and he mentioned it. Its chain of transmission is sahih. Hakim said, "Sahih according to the criterion of Muslim." The word "silah" refers to a place near Khaybar, as Abu Dawud reported from Zuhri. And his saying "their masalih" means their frontier posts, where groups of men keep watch over their enemy.